Valve plunger construction



July 26, 1932. D. R. YARNALL I VALVE PLUNGER CONSTRUCTIONv Filed Nov. 29, 19:50

Patented July 26, 1932 UNITED STATES T T; OFFICE Y DAVID ROBERT AR ALL, or GEI tMANTOWN, rNNNsYLvilNrA, 'AssioNoR 'ro YABNALL- wAnING COMPANY, or PHILADELPHIA; PENNSYLVANIA, A CORPORATION or PENIN- SYLVANIA VALVTEl PLUNGER. ooNs'rRuo'rro Applieationifiled November 29, 1930; Serial 1T0. 498,975.

My invention relates to plungers for seatless blow-oft valves.

The main purpose of my invention is to construct a plunger for a seatless blow-oft 5 valve in two parts ofdifi'erent metah one soft and the other hard, and then weld them together. 1 1 I A further purpose is to provide interfitting members of soft and hard metal to form a plunger for a seatless blow-off valve.

A further purpose is to force a soft ma-- chined cast carbon steel head into a hardened material such as nitrided'nitralloy, welding these two members together to form a '15 plunger.

A further purpose is to make available for valve use the excellent qualities of such special steels as nitralloy.

Further purposes will appear in the specifi- 29 cation and in the claims.

I have preferred to illustrate my invention in one main form only, selecting a form however that is practical and efiicient in operation and which well illustrates the principles involved.

Figure 1 is a sectional view of a seatless blow-off valve.

Figure 2 is a top plan view of the plug that forms the upper portion of my improved plunger.

Figure 3 is a sectional perspective view of the upper plug member taken on the line 33 of Figure 2.

Figure 4 is a sectional perspective View of the lower plug tube taken on the line 3-3 of Figure 2. i a

In the drawing similar numerals indicate like parts.

In the manufacture of the so-called seatless type of valvesthe plunger has always presented difficulty. Part 'of-this hasbeen the requirement that the top of the plunger shall carry the thread for the movement of the plunger and part of it has been due to increasingly severe requirements for the *surface of the plunger because of the rapidincrease in the pressures and corresponding temperatures of the fluids which must be handled by the valve.

I have found it very desirable to use 7 order of 1000 F., giving a form of surface hardening quite similar to case hardeningbut head made of an ordinary steel within which special steels for the plunger in order to secure the advantages from hardening of the steel are ithas been manufactured." The best of these. steels for the purpose are ofthe' general type of that called nitralloy, though other special steels are useful also. i

These steels are hardened or nitrided"by subjection for a long period of time to ammoniagas preferably at temperatures of the 'plungers require for, the reason that blow holes andsoft spots appear in the castings and make themunreliable. In addition the nitralloyis approximately three times as expenslv'e as plain steel and the waste through the loss of the castings involves considerable expense,

Because of the impracticability of forming these plungers of nitralloy castings, forgings have been tried, but they involve difiiculty in finishing which. would be serious With ordinary steel and which becomes pro hibitive with such steels; I

-I findthat this difliculty can be overcome by using a forging of the special steel for the plug type of plunger and a separate plug the threads are formed. Ihave succeeded 'in welding'the' two different parts together.

The valvebody l shown in Figure 1 is bored at 5 and counterbored at 6, forming a seat for a lower packing 7, held in place by a shell 8," here forming a liner. Thisliner is Describing in illustration and not inlimitathe effective valve interiorand is aperture-d yoke 15, secured by suit-able bolts 16 through flanges 17 and 18. Wheel 19 is united rigidly to stem 20, which has bearing in the yoke at 21, and is prevented fromlongitudinal movement, in any suitable manner.

The stem 20 is threaded into the plunger plug head 22 so as to lift and lower the plug tube or operative part of the plunger, here a rigidly attached sleeve 23, preferably welded at 24 to the plug head 22.

The plunger is held against rotation by guides 25 travelling in projections 26 within the yoke. The sleeve is provided with openings 27 which are thus effectively openings in the plunger.

I provide a chamfer 28 at the upper end of the sleeve 23 and the plug head 22 is correspondingly chamfered at 29 to provide proper space for the welding operation.

The plug head 22 has a downwardly depending sleeve 30 that is forced into the counterbore 31 in the plunger 23.

The plunger tube forging of nitralloy is first machined out and then heat-treated until it becomes very hard.

The plug head 22 of soft cast carbon steel is machined and is forced into the upper counterbored end of the tube.

I find that these widely different materials can be Welded reliably to produce a very desirable plunger as if it were all nitralloy.

Though I have described the valve shown at some length in order that such illustration as I make may be clear, I wish it understood .5 that for my present purpose the illustration is intended to be diagrammatic rather than specific, and that I have no thought of confining the application of the invention to this particular valve.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. A valve plunger comprising a body of nitrided steel, a head within which the operating thread is included, of unnitrided material and a fused connection between the two.

2. A valve plunger comprising acase hardened steel plunger and a soft steel head therefor welded to the plunger and carrying a thread for receiving a threaded member adapted to move the plunger.

3. A valve plunger comprising a case hardened plunger having a bore adapted to receive the valve operating screw and a counterbore above the bore, a head fitting within the counterbore and carrying an internal thread for receiving the screw and a fused connection between the plunger and head at the top of the counterbore.

4. A valve plunger of nitrided steel, a head therefor of unnitrided steel fitting within the body of the valve plunger and carrying a thread for receiving a threaded member adapted to operate the plunger and a weld between the plunger and head retaining the head within the body of the plunger.

5. A valve plunger of forged and hardened steel and a cast steel head therefor having an internal thread therein and welded to the plunger.

DAVID ROBERT YARNALL. 

